Heat sink area for 10 watt LED?

[Bill Bowden]

What heat sink area would I need for this 10 watt white LED? The sink
area on the LED is 7/8 inch by 9/16 or a little less since the corners
are rounded. The max temp spec is 60c and ambient may be 38c. I was
thinking of using single sided copper PC board if it isn't too large.
Solid copper would be better. How many square inches would be needed
for the single sided copper?

http://www.ebay.com/itm/1x-10W-White-Power-LED-LightBulb-10Watt-/310414874331?pt=LH_DefaultDomain_0&hash=item48462b16db

-Bill

 

[Jasen Betts]

On 2012-07-23, Bill Bowden <bperryb@bowdenshobbycircuits.info> wrote:

What heat sink area would I need for this 10 watt white LED? The sink
area on the LED is 7/8 inch by 9/16 or a little less since the corners
are rounded. The max temp spec is 60c and ambient may be 38c. I was
thinking of using single sided copper PC board if it isn't too large.
Solid copper would be better. How many square inches would be needed
for the single sided copper?

http://www.ebay.com/itm/1x-10W-White-Power-LED-LightBulb-10Watt-/310414874331?pt=LH_DefaultDomain_0&hash=item48462b16db

pretty large. a TO220 package has about 70K/W and are about 200mm^2 and you want 2K/W so
atleast 9000mm^2 - about the area of both sides of a credit-card
but only if you use really thick copper. I'd start with a piece of
0.5mm copper sheet about 10cm radius and stick a TO220 device in the middle dissipating
10W and see how hot it gets.

--
⚂⚃ 100% natural

--- Posted via news://freenews.netfront.net/ - Complaints to news@netfront.net ---

 

[fungus]

On Monday, July 23, 2012 4:04:36 AM UTC+2, Bill Bowden wrote:

What heat sink area would I need for this 10 watt white LED? The sink
area on the LED is 7/8 inch by 9/16 or a little less since the corners
are rounded. The max temp spec is 60c and ambient may be 38c. I was
thinking of using single sided copper PC board if it isn't too large.
Solid copper would be better. How many square inches would be needed
for the single sided copper?

Massive.

I've bought quite a few of those LEDs on eBay
and they get HOT. So hot in fact that I usually
run them at half the stated power without
active cooling.

(Output is a curve so they put out about 70%
of full light at half power).

Something like this heatsink is the minimum
you'll need for that LED:

http://www.ebay.com/itm/270940654435

Even so you'll probably need a fan to keep
it below 60c at that30c ambient (assuming
you run it at 10W).

Copper PC board? Nah.

 

[John Larkin]

On Sun, 22 Jul 2012 19:04:36 -0700 (PDT), Bill Bowden
<bperryb@bowdenshobbycircuits.info> wrote:

What heat sink area would I need for this 10 watt white LED? The sink
area on the LED is 7/8 inch by 9/16 or a little less since the corners
are rounded. The max temp spec is 60c and ambient may be 38c. I was
thinking of using single sided copper PC board if it isn't too large.
Solid copper would be better. How many square inches would be needed
for the single sided copper?

http://www.ebay.com/itm/1x-10W-White-Power-LED-LightBulb-10Watt-/310414874331?pt=LH_DefaultDomain_0&hash=item48462b16db

-Bill

I'm guessing that an infinite sheet of 1 oz, single-sided copperclad
FR4 wouldn't be enough. The lateral heat conductivity of 1 oz
copperclad is about 70 K/w per square.


--

John Larkin Highland Technology, Inc

jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation

 

[Jim Thompson]

On Mon, 23 Jul 2012 16:17:15 -0700, John Larkin
<jlarkin@highlandtechnology.com> wrote:

On Sun, 22 Jul 2012 19:04:36 -0700 (PDT), Bill Bowden
bperryb@bowdenshobbycircuits.info> wrote:

What heat sink area would I need for this 10 watt white LED? The sink
area on the LED is 7/8 inch by 9/16 or a little less since the corners
are rounded. The max temp spec is 60c and ambient may be 38c. I was
thinking of using single sided copper PC board if it isn't too large.
Solid copper would be better. How many square inches would be needed
for the single sided copper?

http://www.ebay.com/itm/1x-10W-White-Power-LED-LightBulb-10Watt-/310414874331?pt=LH_DefaultDomain_0&hash=item48462b16db

-Bill

I'm guessing that an infinite sheet of 1 oz, single-sided copperclad
FR4 wouldn't be enough. The lateral heat conductivity of 1 oz
copperclad is about 70 K/w per square.

Wow! That bad? Good number to know, though I now have a peck basket
full of heatsinks from the JVC projection set tear-down...

http://www.analog-innovations.com/SED/JVC_TV_KnockDown.pdf

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Bret Cahill]

Something like this heatsink is the minimum
you'll need for that LED:

http://www.ebay.com/itm/270940654435

Even so you'll probably need a fan to keep
it below 60c at that30c ambient (assuming
you run it at 10W).

Cooling in air requires a large area, fins, etc., because of the low
heat transfer coefficient of air, ~ 10 watts/m^2-C.

For some stationary applications instead of going for a huge surface
area it may be useful to use gas - particle bed fluidization with
shorter fins.

This would get the heat transfer coefficient up to 200 w/m^2-C.

The fan or blower might need to output a somewhat higher pressure but
the column shouldn't be very high in most electronics applications so
a few kPa would do.

The optimum particle dia. for maximum heat transfer is about 10
microns -- dust -- but larger sizes will also work.

Fluidized particle bed cloumns are easy home brew.

On the down side

1. this requires gravity so the orientation must be pretty much
upright.

2. it would need to be visible or monitored somehow to make sure it
was working properly.


Bret Cahill

 

[Bill Bowden]

On Jul 23, 12:53 am, fungus <to...@artlum.com> wrote:

On Monday, July 23, 2012 4:04:36 AM UTC+2, Bill Bowden wrote:
What heat sink area would I need for this 10 watt white LED? The sink
area on the LED is 7/8 inch by 9/16 or a little less since the corners
are rounded. The max temp spec is 60c and ambient may be 38c. I was
thinking of using single sided copper PC board if it isn't too large.
Solid copper would be better. How many square inches would be needed
for the single sided copper?


Massive.

I've bought quite a few of those LEDs on eBay
and they get HOT. So hot in fact that I usually
run them at half the stated power without
active cooling.

You're right. I found a large aluminum sink that keeps the sink side
of the LED barely warm to the touch at half power. But the lighted
face of the LED gets very hot. I can only touch it for a couple
seconds.

Any idea how efficient these LEDs are in terms of light output verses
heat?

-Bill

(Output is a curve so they put out about 70%
 of full light at half power).

Something like this heatsink is the minimum
you'll need for that LED:

http://www.ebay.com/itm/270940654435

Even so you'll probably need a fan to keep
it below 60c at that30c ambient (assuming
you run it at 10W).

Copper PC board? Nah.

 

[fungus]

On Thursday, July 26, 2012 2:44:33 AM UTC+2, Bill Bowden wrote:

I've bought quite a few of those LEDs on eBay
and they get HOT. So hot in fact that I usually
run them at half the stated power without
active cooling.


You're right. I found a large aluminum sink that keeps the sink side
of the LED barely warm to the touch at half power. But the lighted
face of the LED gets very hot. I can only touch it for a couple
seconds.

I accidentally dropped a piece of
paper on one once and it burned
right through it in seconds.

You don't want to touch the
front with your finger...

Any idea how efficient these LEDs are in terms of light output verses
heat?

It's a curve that drops off as you
increase the current going through
them. That's why I don't try to run
them at full power - those last few
hundred milliamps mostly get converted
to heat, not light.

 

[John Larkin]

On Tue, 24 Jul 2012 09:33:45 -0700 (PDT), Bret Cahill
<BretCahill@peoplepc.com> wrote:

Something like this heatsink is the minimum
you'll need for that LED:

http://www.ebay.com/itm/270940654435

Even so you'll probably need a fan to keep
it below 60c at that30c ambient (assuming
you run it at 10W).

Cooling in air requires a large area, fins, etc., because of the low
heat transfer coefficient of air, ~ 10 watts/m^2-C.

That number makes no sense.

A small fan directed properly at a small heatsink gets down to 3 K/w
easily, fine to sink a 10 watt LED.

For some stationary applications instead of going for a huge surface
area it may be useful to use gas - particle bed fluidization with
shorter fins.

Crazy impractical.

This would get the heat transfer coefficient up to 200 w/m^2-C.

The fan or blower might need to output a somewhat higher pressure but
the column shouldn't be very high in most electronics applications so
a few kPa would do.

The optimum particle dia. for maximum heat transfer is about 10
microns -- dust -- but larger sizes will also work.

Great! Let's fill our electronic racks with dust. We could reverse our
dust filters and use them to keep the dust *in*


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

 

[Bret Cahill]

Something like this heatsink is the minimum
you'll need for that LED:

http://www.ebay.com/itm/270940654435

Even so you'll probably need a fan to keep
it below 60c at that30c ambient (assuming
you run it at 10W).

Cooling in air requires a large area, fins, etc., because of the low
heat transfer coefficient of air, ~ 10 watts/m^2-C.

That number makes no sense.

The heat transfer coefficient is more or less proportional to the
conductivity of the air / thickness of laminar boundary layer.

You are comfortable [sustainable] sleeping at 22 degrees C with no
blanket. Your 2m^2 skin area has an average temp of 30 degrees C.

8 degrees C X 2 m^2 X 10 watts/m^2 - C = 160 watts

160 watts is about the heat a human needs to sink sleeping.

With a fan the boundary layer gets thinner and heat transfer
coefficient increases but then the delta T would decrease and you
could save some money on the AC.

A small fan directed properly at a small heat sink gets down to 3 K/w
easily, fine to sink a 10 watt LED.

The heat sink in the photo looked like it was about 17 cm in diameter.

For some stationary applications instead of going for a huge surface
area it may be useful to use gas - particle bed fluidization with
shorter fins.

Crazy impractical.

The "distributor" basically an air hockey type plenum, would need more
of a pressure drop than an axial cooling fan but a centrifugal blower
should be enough.

I made a column using glass micro spheres in a 7 cm dia. glass tube,
about 45 cm high. The air was from a shop compressor regulated way
down. Glass bubbles don't transfer much heat but the packed bed
increased in height by 5X and behaves almost like a white liquid,
i.e., ripples and waves.

There's no reason it couldn't scale down to 1 cm diameter items.

This would get the heat transfer coefficient up to 200 w/m^2-C.

The fan or blower might need to output a somewhat higher pressure but
the column shouldn't be very high in most electronics applications so
a few kPa would do.

The optimum particle dia. for maximum heat transfer is about 10
microns -- dust -- but larger sizes will also work.

Great! Let's fill our electronic racks with dust. We could reverse our
dust filters and use them to keep the dust *in*

Three phase gas/solid/liquid fluidization has the all time highest
heat transfer coefficient for cooling, millions of watts/m^2-C --
comparable to the magnitude of the coefficients in steam burn
condensation.

There will be some limits to the scalability because optimum diameter
of the solid particles for maximum cooling is about 1 cm.

Are there any base ball sized electronic devices that would become
possible with megawatts of cooling? This might be what is necessary
to get that circuit to last more than a few milliseconds.


Bret Cahill

 

[Jasen Betts]

On 2012-07-27, Bret Cahill <Bret_E_Cahill@yahoo.com> wrote:

Three phase gas/solid/liquid fluidization has the all time highest
heat transfer coefficient for cooling, millions of watts/m^2-C --
comparable to the magnitude of the coefficients in steam burn
condensation.

There will be some limits to the scalability because optimum diameter
of the solid particles for maximum cooling is about 1 cm.

Are there any base ball sized electronic devices that would become
possible with megawatts of cooling? This might be what is necessary
to get that circuit to last more than a few milliseconds.

Heat pipes have been used successfully for many years without chunks
in them, they just use a liquid-gas phase change fluid (eg: freon, ether or
propane) the fluid boils at the hot and the vapour rises into the
radiator where it condenses,

--
⚂⚃ 100% natural

--- Posted via news://freenews.netfront.net/ - Complaints to news@netfront.net ---

 

[John Larkin]

On 28 Jul 2012 11:46:00 GMT, Jasen Betts <jasen@xnet.co.nz> wrote:

On 2012-07-27, Bret Cahill <Bret_E_Cahill@yahoo.com> wrote:

Three phase gas/solid/liquid fluidization has the all time highest
heat transfer coefficient for cooling, millions of watts/m^2-C --
comparable to the magnitude of the coefficients in steam burn
condensation.

There will be some limits to the scalability because optimum diameter
of the solid particles for maximum cooling is about 1 cm.

Are there any base ball sized electronic devices that would become
possible with megawatts of cooling? This might be what is necessary
to get that circuit to last more than a few milliseconds.

Heat pipes have been used successfully for many years without chunks
in them, they just use a liquid-gas phase change fluid (eg: freon, ether or
propane) the fluid boils at the hot and the vapour rises into the
radiator where it condenses,

Water cooling is common with very high power densities, too.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

 

[Michael A. Terrell]

Bret Cahill wrote:

A place in Tampa made water cooled transformers for Disney World light
displays. Instead of wire coils they coiled up 1" - 2" copper tubing
and pumped coolant inside of the [electrical] conductor.

Ice + air + water would definitely make those puppies cooler although
I haven't done or heard anything about 3 phase _internal_ flow.

Big deal. Water cooled tubing is a very old technology. Take a look
at the 'cooling pond' outside trhe old 500 KW WLW transmitter site, then
look at the date it was built.

 

[Bret Cahill]

Three phase gas/solid/liquid fluidization has the all time highest
heat transfer coefficient for cooling, millions of watts/m^2-C --
comparable to the magnitude of the coefficients in steam burn
condensation.

There will be some limits to the scalability because optimum diameter
of the solid particles for maximum cooling is about 1 cm.

Are there any base ball sized electronic devices that would become
possible with megawatts of cooling?  This might be what is necessary
to get that circuit to last more than a few milliseconds.

Heat pipes have been used successfully for many years without chunks
in them, they just use a liquid-gas phase change fluid (eg: freon, ether or
propane)  the fluid boils at the hot and the vapour rises into the
radiator where it condenses,

Water cooling is common with very high power densities, too.

A place in Tampa made water cooled transformers for Disney World light
displays. Instead of wire coils they coiled up 1" - 2" copper tubing
and pumped coolant inside of the [electrical] conductor.

Ice + air + water would definitely make those puppies cooler although
I haven't done or heard anything about 3 phase _internal_ flow.


Bret Cahill

 

[Bret Cahill]

Three phase gas/solid/liquid fluidization has the all time highest
heat transfer coefficient for cooling, millions of watts/m^2-C --
comparable to the magnitude of the coefficients in steam burn
condensation.

There will be some limits to the scalability because optimum diameter
of the solid particles for maximum cooling is about 1 cm.

Are there any base ball sized electronic devices that would become
possible with megawatts of cooling?  This might be what is necessary
to get that circuit to last more than a few milliseconds.

Heat pipes have been used successfully for many years without chunks
in them, they just use a liquid-gas phase change fluid (eg: freon, ether or
propane)  the fluid boils at the hot and the vapour rises into the
radiator where it condenses,

What's the maximum heat transfer coefficient?


Bret Cahill

 

[krw@att.bizzzzzzzzzzzz]

On Sat, 28 Jul 2012 23:24:04 -0400, "Michael A. Terrell"
<mike.terrell@earthlink.net> wrote:

Bret Cahill wrote:

A place in Tampa made water cooled transformers for Disney World light
displays. Instead of wire coils they coiled up 1" - 2" copper tubing
and pumped coolant inside of the [electrical] conductor.

Ice + air + water would definitely make those puppies cooler although
I haven't done or heard anything about 3 phase _internal_ flow.


Big deal. Water cooled tubing is a very old technology. Take a look
at the 'cooling pond' outside trhe old 500 KW WLW transmitter site, then
look at the date it was built.

Mainframes were water cooled in the '70s - '90s. The Hudson River was IBM
P'ok's cooling pond. CMOS made that unnecessary around the mid '90s, though
it's probably still used to cool the air in the buildings.

 

[Michael A. Terrell]

"krw@att.bizzzzzzzzzzzz" wrote:

On Sat, 28 Jul 2012 23:24:04 -0400, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:


Bret Cahill wrote:

A place in Tampa made water cooled transformers for Disney World light
displays. Instead of wire coils they coiled up 1" - 2" copper tubing
and pumped coolant inside of the [electrical] conductor.

Ice + air + water would definitely make those puppies cooler although
I haven't done or heard anything about 3 phase _internal_ flow.


Big deal. Water cooled tubing is a very old technology. Take a look
at the 'cooling pond' outside trhe old 500 KW WLW transmitter site, then
look at the date it was built.

Mainframes were water cooled in the '70s - '90s. The Hudson River was IBM
P'ok's cooling pond. CMOS made that unnecessary around the mid '90s, though
it's probably still used to cool the air in the buildings.

I saw a new Unisys system being scrapped that was water cooled. It
was a prototype for a navigation system for a nuclear sub. It was in a
round rack that was made to fit through the hatch and had a large
eyebolt on the top of the aluminum rack. I tried to buy it for the
scrap price, to put it in my shop but they insisted on destroying it.

 

[Bret Cahill]

Three phase gas/solid/liquid fluidization has the all time highest
heat transfer coefficient for cooling, millions of watts/m^2-C --
comparable to the magnitude of the coefficients in steam burn
condensation.

There will be some limits to the scalability because optimum diameter
of the solid particles for maximum cooling is about 1 cm.

Are there any base ball sized electronic devices that would become
possible with megawatts of cooling?  This might be what is necessary
to get that circuit to last more than a few milliseconds.

Heat pipes have been used successfully for many years without chunks
in them, they just use a liquid-gas phase change fluid (eg: freon, ether or
propane)  the fluid boils at the hot and the vapour rises into the
radiator where it condenses,

The heat transfer coefficient of evaporation or boiling water is going
to be less than half of that of condensation of steam -- about the
8,500 W/m^2C range of solid-liquid-gas no-phase-change heat transfer
-- and it drops further with organic fluids.

Heat transfer is supposed to be the happen' field in mechanical
engineering yet you can search the ME stacks at a good university
library all day long and maybe find one footnote on fluidized particle
bed heat transfer. Multi-phase is exclusive to process engineering
where an inelegant empiricism rules.

To get an idea of just how much we still live in the dark ages
consider a book published about 10 years ago, _Rheology of Foams_
Heller, et. al., said that the petroleum industry tried to get
viscosities of a lot of foams [the fluffy gas-liquid mixtures] but
almost all the numbers were bad if not useless.

Part of the hold up is the cloistered nature of chemical engineering
where the oil bidness is about as open and transparent as the mafia.
Part of the problem might be a legacy of the cold war where heat
transfer was mistakenly singled out as a strategic field when it isn't
any different than anything else in engineering as far as national
security is concerned.

In any event, it's still the wild west in multiphase. If anyone ever
wants to do a paper requiring lots of lab work, just email.


Bret Cahill

 

[Bill Bowden]

On Jul 26, 6:12 am, fungus <to...@artlum.com> wrote:

On Thursday, July 26, 2012 2:44:33 AM UTC+2, Bill Bowden wrote:

 > I've bought quite a few of those LEDs on eBay
 > and they get HOT. So hot in fact that I usually
 > run them at half the stated power without
 > active cooling.
 

You're right. I found a large aluminum sink that keeps the sink side
of the LED barely warm to the touch at half power. But the lighted
face of the LED gets very hot. I can only touch it for a couple
seconds.

I accidentally dropped a piece of
paper on one once and it burned
right through it in seconds.

You don't want to touch the
front with your finger...

Any idea how efficient these LEDs are in terms of light output verses
heat?

It's a curve that drops off as you
increase the current going through
them. That's why I don't try to run
them at full power - those last few
hundred milliamps mostly get converted
to heat, not light.

Just had a look around ebay and I see this 100 watt RGB LED selling
for around $80. Probably needs a fan to keep it cool?

http://www.ebay.com/itm/1pc-100W-RGB-High-Power-bright-Led-Red-Green-Blue-Energy-Saving-100Watt-Lamp-/160852864342?pt=LH_DefaultDomain_0&hash=item257393ed56

-Bill

 

[fungus]

On Tuesday, July 31, 2012 3:51:13 AM UTC+2, Bill Bowden wrote:

Just had a look around ebay and I see this 100 watt RGB LED selling

Nice!

for around $80. Probably needs a fan to keep it cool?

At that power level you'll need something
like a mid-range PC CPU cooler (with heatpipes
and stuff) to keep it cool.